A checked and not interest button ?

[Tcof]

It will be a big save since "follow manga" can't do the work when you want to try a new manga.
A lot of time i looking for new content, I end up "wait a minutes. I dropped this manga before"

Show it by a icon marked "reading", "not interest" "completed"... or a line color to tell you this one you already touched in front of the thumbnail cover picture.
A hide feature for the one you marked "not interest" also seem useful. By a lot!